Overview
Select the smallest topology that preserves backend OAuth, per-user token isolation, asynchronous job reconciliation, and policy-controlled data handling. Treat scale thresholds as measured local evidence, not Canva product limits.
Prerequisites
- Expected operations, traffic shape, tenants, and recovery objectives
- Data classification, retention policy, and secret backend
- Current scopes, capabilities, preview dependencies, and deployment constraints
Instructions
Step 1: Map trust boundaries
Identify browser, backend, token store, job ledger, worker, data store, and Canva API boundaries. Mark every place customer content or credentials could cross.
Step 2: Choose the base shape
Use a backend monolith for one bounded service, a service plus worker when asynchronous jobs must outlive requests, or isolated services only when ownership and failure domains justify them.
Step 3: Design token rotation
Serialize refresh per Canva user, atomically replace the single-use refresh token, and separate access-token and refresh-token storage.
Step 4: Design job reconciliation
Persist opaque job identity before dispatch, poll with bounded backoff, and reconcile terminal state before repeating a mutating operation.
Step 5: Design policy enforcement
Resolve tenant, resource, explicit scope, capability, preview status, and data policy before dispatch rather than inside a generic HTTP client.
Step 6: Record the decision
Use Write or Edit to capture selected shape, rejected alternatives, assumptions, failure modes, rollback, and validation evidence.
Authentication
Canva Connect calls use Bearer access tokens obtained by a backend through OAuth 2.0 Authorization Code with SHA-256 PKCE. Request explicit least-privilege scopes, keep client secrets and tokens out of browser-visible state, and serialize refresh so the replacement single-use refresh token is stored atomically.
Tool Discipline
Use Read and Grep for discovery and evidence. Use Write or Edit only for the approved artifact, code, configuration, test, or receipt described by this workflow; do not make an unapproved Canva-side change.
Output
- Scoped decision or implementation artifact
- Redacted operation and validation receipt
- Failure, rollback, and follow-up ownership record
Examples
A service exports designs asynchronously for multiple tenants. A backend owns OAuth and policy, a durable ledger owns job identity, and workers are partitioned by tenant without embedding user IDs in metrics.
Error Handling
| Failure | Response |
|---|---|
| Browser-only design proposed | Reject it because client secrets and token exchange require a backend |
| Workers can double-submit | Add durable identity and reconciliation before scaling |
| Topology chosen by guessed volume | Measure queue and failure behavior first |
| Preview dependency blocks review | Separate or disable that feature for the public release |